Electrode assembly, battery cell, battery, and method and apparatus for manufacturing electrode assembly

ABSTRACT

An electrode assembly includes a positive electrode plate and a negative electrode plate wound or stacked to form a bend region, and a barrier layer provided at the bend region. At least part of the barrier layer is located between the positive electrode plate and the negative electrode plate that are adjacent to each other, and is configured to prevent at least part of ions deintercalated from the positive electrode plate from being intercalated into the negative electrode plate in the bend region. A ratio of a thickness of the barrier layer to a porosity of the barrier layer is larger than or equal to 3.5 microns and smaller than or equal to 2000 microns.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application No. 18,055,623, filedNov. 15, 2022, which is a continuation of International Application No.PCT/CN2020/110628, filed Aug. 21, 2020, the entire contents of both ofwhich are incorporated herein by reference.

TECHNICAL FIELD

This application relates to the field of batteries, and in particular,to an electrode assembly, a battery cell, a battery, and a method andapparatus for manufacturing an electrode assembly.

BACKGROUND

A rechargeable battery may be referred to as a secondary battery, and isa battery that can be charged after being discharged to activate activematerials for continuous use. Rechargeable batteries are widely used inelectronic devices, such as mobile phones, laptop computers, batterymotorcycles, electric vehicles, electric airplanes, electric ships,electric toy cars, electric toy ships, electric toy airplanes, andelectric tools.

The rechargeable batteries may include nickel-cadmium batteries,nickel-hydrogen batteries, lithium-ion batteries, secondary alkalinezinc-manganese batteries, and the like.

At present, most commonly used batteries in automobiles are lithium-ionbatteries. As rechargeable batteries, the lithium-ion batteries have theadvantages of small size, high energy density, high power density, largecycle count, long storage time, and so on.

The rechargeable battery includes an electrode assembly and anelectrolyte. The electrode assembly includes a positive electrode plate,a negative electrode plate, and a separator located between the positiveelectrode plate and the negative electrode plate. The positive electrodeplate may also be referred to as a cathode electrode plate, and apositive electrode active material layer is provided on two surfaces ofthe positive electrode plate. For example, a positive electrode activematerial of the positive electrode active material layer may be lithiummanganate oxide, lithium cobalt oxide, lithium iron phosphate, orlithium nickel cobalt manganate. The negative electrode plate may alsobe referred to as an anode electrode plate, and a negative electrodeactive material layer is provided on two surfaces of the negativeelectrode plate. For example, a negative electrode active material ofthe negative electrode active material layer may be graphite or silicon.

As a common abnormal phenomenon of lithium batteries, lithiumprecipitation may affect charging efficiency and energy density oflithium ions. In case of severe lithium precipitation, lithium crystalsmay be further formed, and the lithium crystals may pierce the separatorto cause an internal short circuit and thermal runaway, severelyaffecting battery safety.

Therefore, how to reduce or avoid lithium precipitation and improvebattery safety has become a concern in the industry.

SUMMARY

A plurality of aspects of this application provide an electrodeassembly, a battery cell, a battery, and a method and apparatus formanufacturing an electrode assembly, so as to overcome the foregoingproblem or at least partially resolve the foregoing problem.

A first aspect of this application provides an electrode assembly,including a positive electrode plate and a negative electrode plate,where the positive electrode plate and the negative electrode plate arewound or stacked to form a bend region.

The bend region is provided with a barrier layer; and at least part ofthe barrier layer is located between the positive electrode plate andthe negative electrode plate that are adjacent to each other, and isused to prevent at least part of ions deintercalated from the positiveelectrode plate from being intercalated into the negative electrodeplate in the bend region. The barrier layer is provided between thepositive electrode plate and the negative electrode plate that areadjacent to each other, so that the barrier layer blocks at least partof ions deintercalated from a positive electrode active material layerof the positive electrode plate in the bend region during charging, andthe ions blocked by the barrier layer cannot be intercalated into anegative electrode active material layer of the negative electrode plateadjacent to the positive electrode plate in the bend region. In thisway, in a case that the negative electrode active material layer of thenegative electrode plate falls off, lithium precipitation is reduced,thereby improving safety performance of battery cells and improvingservice life of the battery cells.

In some embodiments, the electrode assembly further includes a separatorfor isolating the positive electrode plate and the negative electrodeplate that are adjacent to each other; and the barrier layer is attachedto one or two surfaces of the positive electrode plate, and/or thebarrier layer is attached to one or two surfaces of the negativeelectrode plate, and/or the barrier layer is attached to one or twosurfaces of the separator. This can reduce positional movement of thebarrier layer during use of the electrode assembly.

In some embodiments, the electrode assembly further includes a separatorfor isolating the positive electrode plate and the negative electrodeplate that are adjacent to each other; and the barrier layer isindependently provided between the positive electrode plate and theseparator that are adjacent to each other in the bend region, or thebarrier layer is independently provided between the negative electrodeplate and the separator that are adjacent to each other in the bendregion. This facilitates installation of the barrier layer.

In some embodiments, a porosity of the barrier layer is less than aporosity of the separator. In this way, the barrier layer can moreeffectively block passage of lithium ions.

In some embodiments, the electrode assembly includes one positiveelectrode plate and one negative electrode plate; the one positiveelectrode plate and the one negative electrode plate are compacted andwound to form one winding structure; and the barrier layer is providedbetween the positive electrode plate and the negative electrode platethat are adjacent to each other on at least an innermost side of thebend region. In this way, lithium precipitation between the positiveelectrode plate and the negative electrode plate that are adjacent toeach other on the innermost side can be reduced, improving safetyperformance.

In some embodiments, an innermost electrode plate in the bend region isa negative electrode plate. This can improve utilization efficiency ofan active material of the positive electrode plate.

In some embodiments, there are a plurality of discontinuous barrierlayers; and the plurality of discontinuous barrier layers are spacedapart from each other in a bending direction or the plurality ofdiscontinuous barrier layers are spaced apart from each other in adirection perpendicular to the bending direction. In this way, passageof some lithium ions can be blocked, reducing lithium precipitation andalso ensuring energy density of the electrode assembly.

In some embodiments, a thickness of the barrier layer is 2 to 200microns, or 5 to 100 microns. This can ensure safety of the electrodeassembly and also ensure energy density of the electrode assembly.

In some embodiments, the barrier layer is provided with at least onethrough hole.

In some embodiments, the porosity of the barrier layer is 10% to 70%, or20% to 60%. This can ensure safety of the electrode assembly and alsoensure energy density of the electrode assembly.

In some embodiments, the thickness of the barrier layer is A microns,the porosity of the barrier layer is B, and A and B satisfy thefollowing relationship: 3.5 microns≤A/B≤2000 microns; or 7microns≤A/B≤1000 microns. This can ensure safety of the electrodeassembly and also ensure energy density of the electrode assembly.

In some embodiments, two ends, in a direction perpendicular to thebending direction, of the negative electrode active material layer ofthe negative electrode plate extends beyond corresponding ends of thepositive electrode active material layer of the positive electrodeplate. This can ensure energy density of the electrode assembly.

In some embodiments, the barrier layer includes two ends in a directionperpendicular to the bending direction, and one or two ends of thebarrier layer extend beyond the positive electrode active material layerof the positive electrode plate. In this way, passage of more lithiumions can be blocked, reducing lithium precipitation.

In some embodiments, the barrier layer includes two ends in a directionperpendicular to the bending direction, and the negative electrodeactive material layer of the negative electrode plate extends beyond oneor two ends of the barrier layer. In this way, passage of some lithiumions can be blocked, reducing lithium precipitation and also ensuringenergy density of the electrode assembly.

In some embodiments, the barrier layer is disposed opposite alargest-curvature portion of the negative electrode plate. In this way,no lithium ions may be intercalated into the largest-curvature portionor only a small part of lithium ions are intercalated into thelargest-curvature portion, thereby reducing lithium precipitation.

In some embodiments, the barrier layer includes at least one of thefollowing: inorganic oxide, binder, or adhesive tape.

In some embodiments, two ends, extending in the bending direction, ofthe barrier layer are located in the bend region. In this way, passageof more lithium ions can be blocked, reducing lithium precipitation.

In some embodiments, the electrode assembly is provided with a flatregion connected to the bend region.

One end, extending in the bending direction, of the barrier layer islocated in the flat region, and the other end is located in the bendregion; or two ends, extending in the bending direction, of the barrierlayer are both located in the flat region.

A second aspect of this application provides a battery cell, including:a housing, a cover plate, and at least one electrode assembly accordingto at least one of the foregoing embodiments.

The housing is provided with an accommodating cavity and an opening, andthe electrode assembly is accommodated in the accommodating cavity; andthe cover plate is configured to close the opening of the housing.

A third aspect of this application provides a battery, including a boxbody and at least one battery cell, and the battery cell is received inthe box body.

A fourth aspect of this application provides a method for manufacturingan electrode assembly, including:

-   -   providing a positive electrode plate, a negative electrode        plate, and a barrier layer; and    -   winding or stacking the positive electrode plate and the        negative electrode plate to form a bend region, where the bend        region is provided with the barrier layer, and at least part of        the barrier layer is located between the positive electrode        plate and the negative electrode plate that are adjacent to each        other, and is used to prevent at least part of ions        deintercalated from the positive electrode plate from being        intercalated into the negative electrode plate in the bend        region.

In some embodiments, a separator for isolating the positive electrodeplate and the negative electrode plate that are adjacent to each otheris provided; and the separator, the positive electrode plate, and thenegative electrode plate are wound or stacked together.

In some embodiments, before the separator, the positive electrode plate,and the negative electrode plate are wound or stacked together, themethod further includes: placing the barrier layer on one or twosurfaces of the positive electrode plate or the negative electrodeplate.

In some embodiments, the placing the barrier layer on one or twosurfaces of the positive electrode plate or the negative electrode platespecifically includes: adhering or coating the barrier layer to one ortwo surfaces of the positive electrode plate or the negative electrodeplate.

A fifth aspect of this application provides a device for manufacturingan electrode assembly, including:

-   -   a first providing apparatus, configured to provide a positive        electrode plate;    -   a second providing apparatus, configured to provide a negative        electrode plate;    -   a third providing apparatus, configured to provide a barrier        layer; and    -   an assembly apparatus, configured to wind or stack the positive        electrode plate and the negative electrode plate to form a bend        region.

The bend region is provided with a barrier layer; and at least part ofthe barrier layer is located between the positive electrode plate andthe negative electrode plate that are adjacent to each other, and isused to prevent at least part of ions deintercalated from the positiveelectrode plate from being intercalated into the negative electrodeplate in the bend region.

In some embodiments, the device for manufacturing an electrode assemblyfurther includes a fourth providing apparatus, configured to provide aseparator for isolating the positive electrode plate and the negativeelectrode plate that are adjacent to each other, where the assemblyapparatus is further configured to wind or stack the positive electrodeplate, the negative electrode plate, and the separator to form the bendregion.

In some embodiments, there are two third providing apparatuses, and thetwo third providing apparatuses each are configured to provide thebarrier layer and adhere or coat the barrier layer to two surfaces ofthe positive electrode plate or the negative electrode plate.

A sixth aspect of this application provides an electric apparatus, wherethe electric apparatus is configured to receive power supplied by abattery.

The foregoing description is merely an overview of the technicalsolutions in the embodiments of this application. In order to betterunderstand the technical means in the embodiments of this application,to achieve implementation according to content of the specification, andto make the above and other objects, features and advantages in theembodiments of this application more comprehensible to understand, thefollowing describes specific embodiments of this application.

BRIEF DESCRIPTION OF DRAWINGS

To describe the technical solutions in the embodiments of thisapplication more clearly, the following briefly describes theaccompanying drawings required for describing the embodiments.Apparently, the accompanying drawings in the following description showmerely some embodiments of this application, and a person of ordinaryskill in the art may still derive other drawings from these accompanyingdrawings without creative efforts.

FIG. 1 is a schematic three-dimensional structural diagram of anelectrode assembly according to an embodiment of this application;

FIG. 2 is a schematic structural diagram of a cross section of theelectrode assembly of FIG. 1 in a direction perpendicular to a windingaxis K;

FIG. 3 is a schematic partial structural diagram of a bend region of anelectrode assembly according to an embodiment of this application;

FIG. 4 is a schematic structural diagram showing distribution of barrierlayers after a bend region of an electrode assembly is flattenedaccording to another embodiment of this application;

FIG. 5 is a schematic structural diagram showing another type ofdistribution of barrier layers after a bend region of an electrodeassembly is flattened according to another embodiment of thisapplication;

FIG. 6 is a schematic structural diagram showing another type ofdistribution of barrier layers after a bend region of an electrodeassembly is flattened according to another embodiment of thisapplication;

FIG. 7 is a schematic structural diagram of a negative electrode plateaccording to another embodiment of this application;

FIG. 8 is a schematic structural diagram of a positive electrode plateaccording to another embodiment of this application;

FIG. 9 is a schematic structural diagram of a cross section in adirection A-A in FIG. 8 ;

FIG. 10 is a schematic structural diagram of a cross section in adirection B-B in FIG. 8 ;

FIG. 11 is a schematic structural diagram of a cross sectionperpendicular to a winding axis of a flat-shaped electrode assemblyaccording to another embodiment of this application;

FIG. 12 is a schematic structural diagram of a cross sectionperpendicular to a winding axis of another flat-shaped electrodeassembly according to another embodiment of this application;

FIG. 13 is a schematic structural diagram of a cross sectionperpendicular to a winding axis of another flat-shaped electrodeassembly according to another embodiment of this application;

FIG. 14 is a schematic structural diagram of a cross sectionperpendicular to a winding axis of another flat-shaped electrodeassembly according to another embodiment of this application;

FIG. 15 is a schematic structural diagram of a cross sectionperpendicular to a winding axis of another flat-shaped electrodeassembly according to another embodiment of this application;

FIG. 16 is a schematic structural diagram of a cross sectionperpendicular to a winding axis of another flat-shaped electrodeassembly according to another embodiment of this application;

FIG. 17 is a schematic structural diagram of a cross sectionperpendicular to a winding axis of another flat-shaped electrodeassembly according to another embodiment of this application;

FIG. 18 is a schematic structural diagram of a cross sectionperpendicular to a winding axis of a flat-shaped electrode assemblyaccording to another embodiment of this application;

FIG. 19 is a schematic structural diagram of a cross sectionperpendicular to a winding axis of a flat-shaped electrode assemblyaccording to another embodiment of this application;

FIG. 20 is a schematic structural diagram of a battery cell according toanother embodiment of this application;

FIG. 21 is a schematic structural diagram of a battery module accordingto another embodiment of this application;

FIG. 22 is a schematic structural diagram of a battery according toanother embodiment of this application;

FIG. 23 is a schematic structural diagram of an electric apparatusaccording to another embodiment of this application;

FIG. 24 is a schematic flowchart of a method for manufacturing anelectrode assembly according to another embodiment of this application;and

FIG. 25 is a schematic structural diagram of a device for manufacturingan electrode assembly according to another embodiment of thisapplication.

DETAILED DESCRIPTION OF EMBODIMENTS

To make the objectives, technical solutions, and advantages of theembodiments of this application clearer, the following clearly describesthe technical solutions in the embodiments of this application withreference to the accompanying drawings in the embodiments of thisapplication. Apparently, the described embodiments are some but not allof the embodiments of this application. All other embodiments obtainedby a person of ordinary skill in the art based on the embodiments ofthis application without creative efforts shall fall within theprotection scope of this application.

Unless otherwise defined, all technical and scientific terms used hereinshall have the same meanings as commonly understood by those skilled inthe art to which this application belongs. The terms used in thespecification of this application are merely intended to describe thespecific embodiments but not intended to constitute any limitation onthis application. The terms “include”, “have” and any other variants inthe specification, claims, and description of accompanying drawings ofthis application mean to cover the non-exclusive inclusion.

The term “embodiment” described herein means that specific features,structures, or characteristics in combination with descriptions of theembodiments may be incorporated in at least one embodiment of thisapplication. The word “embodiment” in various positions in thespecification does not necessarily refer to a same embodiment, or anindependent or alternative embodiment that is exclusive of otherembodiments. Persons skilled in the art explicitly and implicitlyunderstand that the embodiments described herein may combine withanother embodiments.

The term “and/or” in this specification describes only an associationrelationship for describing associated objects and represents that threerelationships may exist. For example, A and/or B may represent thefollowing three cases: A alone, both A and B, and B alone. In addition,the character “/” in this specification generally indicates an “or”relationship between the associated objects.

In the descriptions of this application, it should be understood thatthe orientations or positional relationships indicated by the terms“center”, “vertical”, “transverse”, “length”, “width”, “thickness”,“upper”, “lower”, “front”, “rear”, “left”, “right”, “perpendicular”,“horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”,“counterclockwise”, “axial”, “radial”, “circumferential”, and the likeare based on the orientations or positional relationships shown in theaccompanying drawings, are merely intended to facilitate thedescriptions of this application and simplify the descriptions, are notintended to indicate or imply that the apparatuses or componentsmentioned in this application must have specific orientations, or beconstructed and operated for a specific orientation, and therefore shallnot be construed as a limitation to this application. In addition, theterms “first”, “second” and the like in the specification, claims ordescription of accompanying drawings of this application are used todistinguish between different objects but not describe a specificsequence, and can explicitly or implicitly include one or more features.In the descriptions of this application, unless otherwise specified,“plurality” means two or more than two.

In the descriptions of this application, it should be noted that unlessotherwise specified and defined explicitly, the terms “install”, “link”,and “connection” should be understood in their general senses. Forexample, the terms may be a fixed connection, a detachable connection,or an integrated connection; or may be a mechanical connection or anelectrical connection; or may be a direct connection, or an indirectconnection through an intermediate medium; or may be an internalconnection between two components. A person of ordinary skill in the artcan understand specific meanings of these terms in this applicationbased on specific situations.

In order to make a lithium-ion battery smaller in volume and higher inenergy density, a positive electrode plate, a negative electrode plate,and a separator in an electrode assembly of the lithium-ion battery maybe wound and then compacted. For example, FIG. 1 is a schematicthree-dimensional structural diagram of an electrode assembly. Theelectrode assembly includes a negative electrode plate, a positiveelectrode plate, and a separator. The negative electrode plate, thepositive electrode plate, and the separator are stacked and wound arounda winding axis K to form a winding structure. The separator is aninsulation film and used to isolate the negative electrode plate fromthe positive electrode plate to prevent short circuit of the negativeelectrode plate and the positive electrode plate. The winding structureof the electrode assembly is of a flat shape. A schematic structuraldiagram of a cross section of the electrode assembly in a directionperpendicular to the winding axis K may be shown in FIG. 2 .

With reference to FIG. 1 and FIG. 2 , the electrode assembly includes aflat region 100 and bend regions 200 located at two ends of the flatregion 100. The flat region 100 is a region with a parallel structure inthe winding structure, that is, the negative electrode plate 101, thepositive electrode plate 102, and the separator 103 in the flat region100 are substantially parallel to each other. In other words, surfacesof the negative electrode plate 101, the positive electrode plate 102,and the separator 103 in the flat region 100 of the electrode assemblyare all flat. The bend region 200 is a region with a bending structurein the winding structure, that is, the negative electrode plate 101, thepositive electrode plate 102, and the separator 103 in the bend region200 are all bent. In other words, surfaces of the negative electrodeplate 101, the positive electrode plate 102, and the separator 103 inthe bend region 200 of the electrode assembly are all curved. The bendregion 200 has a bending direction L, and the bending direction L can beunderstood as a direction in which surfaces of the electrode assembly inthe bend region points to the flat region. For example, the bendingdirection L is a winding direction of the winding structure in the bendregion 200.

A surface of the negative electrode plate 101 has a negative electrodeactive material layer composed of a negative electrode active material,and a surface of the positive electrode plate 102 has a positiveelectrode active material layer composed of a positive electrode activematerial. For example, the positive electrode active material may belithium manganate oxide, lithium cobalt oxide, lithium iron phosphate,or lithium nickel cobalt manganate, and the negative electrode activematerial may be graphite or silicon.

During charging of the lithium-ion battery, lithium ions aredeintercalated from the positive electrode and intercalated into thenegative electrode. However, some exceptions may occur, for example,insufficient space for lithium intercalation in the negative electrode,excessively large resistance for intercalation of lithium ions into thenegative electrode, excessively rapid deintercalation of lithium ionsfrom the positive electrode, inability of intercalating deintercalatedlithium ions into the negative electrode active material layer of thenegative electrode plate in the same amount, or lithium ions that cannotbe intercalated into the negative electrode plate obtaining electronsonly on the surface of the negative electrode. Consequently, asilver-white metallic lithium element is formed, which is referred to aslithium precipitation. Lithium precipitation not only reducesperformance of lithium-ion batteries and greatly shortens the cyclelife, but also limits a fast charging capacity of the lithium-ionbatteries. In addition, when lithium precipitation occurs in thelithium-ion battery, resulting lithium metal is so active to react withthe electrolyte at a lower temperature, causing a lower self-heatingstart temperature (Tonset) and a higher self-heating rate, and thereforeseverely affecting battery safety. Furthermore, in case of severelithium precipitation, deintercalated lithium ions may form lithiumcrystals on the surface of the negative electrode plate, and the lithiumcrystals are prone to pierce the separator, to cause a risk of shortcircuit to the positive electrode plate and the negative electrode platethat are adjacent to each other.

During the research and development process, the inventor found thatlithium precipitation often occurs in the bend region of the electrodeassembly. Through further research, the inventor found that lithiumprecipitation is attributed to falling-off of the active material. Thepositive active material is coated on the surface of the positiveelectrode plate, and the negative active material is coated on thesurface of the negative electrode plate; however, the positive electrodeplate and the negative electrode plate that are located in the bendregion need to be bent, and therefore the active materials may fall off,which is referred to as powder falling-off. This especially occurs on aninnermost-layer electrode plate in the bend region due to a largestbending degree of the innermost-layer electrode plate that easily causesfalling-off of the active material. Due to falling-off of the activematerials, especially falling-off of the active material on the negativeelectrode plate, lithium intercalation positions on the negativeelectrode active material layer of the negative electrode plate may beless than lithium ions that can be provided by the positive electrodeactive material layer of the positive electrode plate adjacent to thenegative electrode plate. As a result, the lithium battery is prone tolithium precipitation during charging.

In view of this, this application is intended to provide an electrodeassembly. The electrode assembly includes a negative electrode plate, apositive electrode plate, and a separator. The negative electrode plate,the positive electrode plate, and the separator may be stacked and woundin a winding axis to form a winding structure, for example, aflat-shaped winding structure. The negative electrode plate, thepositive electrode plate, and the separator may be continuously foldedin a zigzag manner after being stacked. Regardless of whether theelectrode assembly is formed in a winding or zigzag manner, theelectrode assembly includes a flat region and bend regions connectingtwo ends of the flat region. In order to reduce or avoid lithiumprecipitation, a barrier layer is provided between any positiveelectrode plate and negative electrode plate that are adjacent to eachother in the bend region. The barrier layer is especially providedbetween the positive electrode plate and negative electrode plate thatare adjacent to each other on an innermost side of the bend region. Thebarrier layer is used to block at least part of lithium ionsdeintercalated from the positive electrode active material layer of thepositive electrode plate in the bend region, so that the ions blocked bythe barrier layer cannot be intercalated into the negative electrodeactive material layer of the negative electrode adjacent to the positiveelectrode plate in the bend region. In this way, a quantity of lithiumintercalation positions on the negative electrode active material layerof the negative electrode plate in the bend region is substantially thesame as a quantity of lithium ions that can be provided by the positiveelectrode active material layer of the positive electrode plate adjacentto the negative electrode plate, thereby reducing or avoiding lithiumprecipitation.

Regardless of whether the electrode assembly is formed in the winding orzigzag manner, the electrode assembly includes the flat region and thebend regions connecting two ends of the flat region. For ease ofdescription, the electrode assembly in this embodiment is described byusing the flat-shaped winding structure as an example. For example, onebend region C and a flat region P of the flat-shaped winding structuremay be shown in FIG. 3 . FIG. 3 is a schematic partial structuraldiagram of a bend region of an electrode assembly according to anembodiment of this application. In the bend region C, the electrodeassembly includes a positive electrode plate 1, a negative electrodeplate 2, and a separator 3 for isolating the positive electrode plate 1and the negative electrode plate 2. The separator 3 may be independentlyprovided between the positive electrode plate 1 and the negativeelectrode plate 2 that are adjacent to each other, or may be coated to asurface of the positive electrode plate 1 or the negative electrodeplate 2.

The separator 3 features electronic insulation and is used to isolatethe positive electrode plate 1 and the negative electrode plate 2 thatare adjacent to each other, so as to prevent a short circuit of thepositive electrode plate 1 and the negative electrode plate 2 that areadjacent to each other. The separator 3 is provided with a large numberof through micropores to ensure free passage of electrolyte ions andgood permeability of lithium ions. Therefore, the separator 3 basicallycannot block passage of the lithium ions. For example, the separator 3includes a separator substrate and a functional layer located on asurface of the separator substrate. The separator substrate may be atleast one of polypropylene, polyethylene, ethylene-propylene copolymer,polybutylene terephthalate, or the like. The functional layer may be amixture layer of ceramic oxide and a binder.

For the electrode assembly in this embodiment of this application, thebend region C is further provided with a barrier layer 4; and at leastpart of the barrier layer 4 is located between the positive electrodeplate 1 and the negative electrode plate 2 that are adjacent to eachother, and is used to prevent at least part of ions deintercalated fromthe positive electrode plate 1 from being intercalated into the negativeelectrode plate 2 in the bend region C.

Disposing the barrier layer 4 between the positive electrode plate 1 andthe negative electrode plate 2 that are adjacent to each other in thebend region C can effectively reduce or avoid lithium precipitation. Thebarrier layer 4 is provided between the positive electrode plate 1 andthe negative electrode plate 2 that are adjacent to each other, so thatthe barrier layer 4 blocks at least part of ions deintercalated from apositive electrode active material layer (for example, a positiveelectrode active material layer in the bend region C) of the positiveelectrode plate 1 during charging, and the ions blocked by the barrierlayer 4 cannot be intercalated into a negative electrode active materiallayer of the negative electrode plate 2 in the bend region C. In thisway, when the negative electrode active material layer of the negativeelectrode plate 2 falls off, lithium precipitation is reduced. That is,although the number of lithium intercalation positions on the negativeelectrode plate 2 is reduced due to falling-off of the negativeelectrode active material, lithium precipitation can be reduced or evenavoided because the barrier layer 4 blocks at least part of the lithiumions deintercalated from the positive electrode plate 1 adjacent to thenegative electrode plate 2.

In another embodiment of this application, in order to block passage oflithium ions, the barrier layer 4 may be made of inorganic oxide and/ormacromolecular polymer.

In another embodiment of this application, the inorganic oxide may be atleast one of magnesium oxide (MgO), calcium oxide (CaO), boehmite,wollastonite, barium sulfate (BaSO4), calcium sulfate (CaSO4), calciumcarbonate (CaCO3), aluminum oxide (Al2O3), or silicon dioxide (SiO2).

In another embodiment of this application, the macromolecular polymermay be polypropylene (polypropylene), polyvinyl chloride (PVC),polyethylene (polyethylene, PE), epoxy resin, polyacrylate, andpolyurethane rubber.

In another embodiment of this application, the barrier layer 4 may beadhesive tape or adhesive paper. The adhesive tape includes an adhesiveand a substrate. The substrate may be made of polyethylene and/orethylene-vinyl acetate copolymer (EVA), or the like. The adhesive paperis made of at least one of polyethylene phthalate, polyvinylidenefluoride, polyurethane, sodium polyacrylate, styrene butadiene rubber,polyetherimide, carboxymethyl cellulose, or acrylate.

In another embodiment of this application, one positive electrode plate1 and one negative electrode plate 2 may be stacked and then wound orfolded, or at least one (for example, two or more) positive electrodeplate 1 and at least one (for example, two or more) negative electrodeplate 2 are stacked and then wound or folded, to form a bend region C.When the electrode assembly is provided with a plurality of positiveelectrode plates 1 and a plurality of negative electrode plate 2 in thebend region C, the bend region C includes a structure in which positiveelectrode plates 1 and negative electrode plates 2 are alternatelyarranged, and the barrier layer 4 is included between at least onepositive electrode plate 1 and at least one negative electrode plate 2that are adjacent to each other. The positive electrode plate 1 and thenegative electrode plate 2 that are adjacent to each other in the bendregion C indicate that one positive electrode plate 1 and one negativeelectrode plate 2 are adjacent in the bend region C, without another onepositive electrode plate 1 or another one negative electrode plate 2included in between.

In another embodiment of this application, in addition to the structurein which the positive electrode plate 1 and the negative electrode plate2 are alternately arranged, the bend region C (for example, theinnermost and/or outermost side of the bend region C) may alternativelyhave a structure in which no negative electrode plate 2 is sandwichedbetween two adjacent positive electrode plates 1, or a structure inwhich no positive electrode plate 1 is sandwiched between two adjacentnegative electrode plates 2. In this case, no barrier layer 4 may beprovided between two positive electrode plates 1 or two adjacentnegative electrode plates 2, that is, the barrier layer 4 is providedbetween the positive electrode plate 1 and the negative electrode plate2 that are adjacent to each other.

In another embodiment of this application, the innermost electrode platein the bend region C of the electrode assembly is generally most bent,that is, the active material of the innermost electrode plate has alargest probability of falling-off or the active material falls off mostseverely. The innermost electrode plate may be a positive electrodeplate 1 or a negative electrode plate 2. For example, when the innermostelectrode plate is the negative electrode plate 2, in order to reducelithium precipitation to a maximum extent, the barrier layer 4 isdisposed between the positive electrode plate 1 and the negativeelectrode plate 2 that are adjacent to each other on at least theinnermost side of the bend region C. In this way, lithium precipitationbetween the positive electrode plate and the negative electrode platethat are adjacent to each other on the innermost side can be reduced,improving safety performance. When the innermost electrode plate in thebend region C is the negative electrode plate 2, utilization efficiencyof the active material of the positive electrode plate 1 can beimproved.

The barrier layer 4 is located between the positive electrode plate 1and the negative electrode plate 2 that are adjacent to each other. Thebarrier layer 4 may be independently located between the positiveelectrode plate 1 and the negative electrode plate 2 that are adjacentto each other, or the barrier layer 4 may be attached to any surface ofthe positive electrode plate 1, the negative electrode plate 2, or theseparator 3. That the barrier layer 4 may be independently locatedbetween the positive electrode plate 1 and the negative electrode plate2 that are adjacent to each other means that the barrier layer 4 isstacked with each of the positive electrode plate 1 and the negativeelectrode plate 2 in a separated manner, not being in an adhering orcoating relationship. This facilitates installation of the barrier layer4. Attaching means adhering, coating, or spraying. By means ofattaching, positional movement of the barrier layer 4 can be reducedduring use of the battery cell.

For example, the barrier layer 4 is attached to one or two surfaces ofthe positive electrode plate 1, and/or the barrier layer 4 is attachedto one or two surfaces of the negative electrode plate 2.

In another embodiment of this application, the barrier layer 4 isindependently located between the positive electrode plate 1 and theseparator 3 that are adjacent to each other in the bend region C, or thebarrier layer 4 is independently located between the negative electrodeplate 2 and the separator 3 that are adjacent to each other in the bendregion C, or the barrier layer 4 is attached to one or two surfaces ofthe separator 3. That the barrier layer 4 is independently locatedbetween the positive electrode plate 1 and the separator 3 that areadjacent to each other in the bend region C, or the barrier layer 4 isindependently located between the negative electrode plate 2 and theseparator 3 that are adjacent to each other in the bend region Cindicates that the barrier layer 4 is separately stacked with thepositive electrode plate 1, the negative electrode plate 2, and theseparator 3, not being in an adhering or coating relationship.

In another embodiment of this application, two ends, extending in thebending direction L, of the barrier layer 4 are both located in the bendregion C, that is, the barrier layer 4 is completely located in the bendregion C. In this embodiment, the electrode assembly further includes aflat region P connected to the bend region C. The bending direction L isa direction along a curved surface of the bend region C and pointing tothe flat region P, and a direction perpendicular to the bendingdirection L is a direction vertical with the bending direction L.

In another embodiment of this application, one end, extending in thebending direction L, of the barrier layer 4 is located in the flatregion P, and the other end is located in the bend region C.

In another embodiment of this application, in order to block as manylithium ions as possible, the barrier layer 4 has a large area aspossible in the bend region C. For example, two ends, extending in thebending direction L, of the barrier layer 4 are both located in the flatregion P, that is, the barrier layer 4 is not only located in the bendregion C but also extends to the flat region P.

In another embodiment of this application, two ends, extending in thebending direction L, of the barrier layer 4 are both located at ajunction between the bend region C and the flat region P, or two ends,extending in the bending direction L, of the barrier layer 4 are bothclose to a junction between the bend region C and the flat region P.

In another embodiment of this application, for the positive electrodeplate 1 and the negative electrode plate 2 that are adjacent to eachother, when the negative electrode plate 2 is located on the innermostside of the bend region C, falling-off of the active material is mostsevere in a largest-curvature portion of the innermost negativeelectrode plate 2. Therefore, regardless of how the barrier layer 4extends in the bending direction L, the barrier layer 4 prevents, asmany as possible, lithium ions deintercalated from the positiveelectrode plate 1 from being intercalated into the largest-curvatureportion of the negative electrode plate 2, that is, the barrier layer 4is provided opposite to the largest-curvature portion of the negativeelectrode plate 2, so as to cover the largest-curvature portion of thenegative electrode plate 2. In this way, no lithium ions may beintercalated into the largest-curvature portion of the negativeelectrode plate 2 or only a small number of lithium ions areintercalated into the largest-curvature portion of the negativeelectrode plate 2, thereby reducing lithium precipitation.

In another embodiment of this application, the largest-curvature portionof the negative electrode plate 2 on the innermost side of the bendregion C is a line (for example, the line may be a straight line)perpendicular to the bending direction L on a curved surface of thenegative electrode plate 2 on the innermost side of the bend region C. Acurvature of any point on the line is greater than a curvature of acurved surface, on both sides extending from the point in the bendingdirection L, of the negative electrode plate 2 on the innermost side ofthe bend region C. For example, when the negative electrode plate 2 issymmetrically bent in the bending direction L in the bend region C, thelargest-curvature portion of the negative electrode plate 2 on theinnermost side of the bend region C is a middle portion of the negativeelectrode plate 2 in the bend region C.

A larger area of the barrier layer 4 in the bend region C indicates thatmore lithium ions can be blocked. However, more lithium ions blockedindicates lower energy density of the bend region C, resulting in lowerenergy density of the electrode assembly. Therefore, in anotherembodiment of this application, for the positive electrode plate 1 andthe negative electrode plate 2 that are adjacent to each other in thebend region C, an appropriate amount of lithium ions can bedeintercalated from the positive electrode plate 1 and intercalated intothe negative electrode plate 2, ensuring energy density to some extent.

For example, as shown in FIG. 4 , FIG. 4 is a schematic structuraldiagram showing distribution of barrier layers after a bend region of anelectrode assembly is flattened according to another embodiment of thisapplication. A plurality of discontinuous barrier layers 4 are includedbetween the positive electrode plate 1 and the negative electrode plate2 that are adjacent to each other in the bend region C. The plurality ofdiscontinuous barrier layers are spaced apart from each other in thebending direction L, so that part of lithium ions are not blocked by thebarrier layer 4, that is, the part of lithium ions pass between twoadjacent barrier layers 4 and are intercalated into the negativeelectrode active material layer of the negative electrode plate 2. Forexample, the plurality of discontinuous barrier layers 4 are attached tothe surface of the positive electrode plate 1. In this way, passage ofsome lithium ions can be blocked, reducing lithium precipitation andalso ensuring energy density of the electrode assembly.

For another example, as shown in FIG. 5 , FIG. 5 is a schematicstructural diagram showing another type of distribution of barrierlayers after a bend region of an electrode assembly is flattenedaccording to another embodiment of this application. A plurality ofdiscontinuous barrier layers 4 are included between the positiveelectrode plate 1 and the negative electrode plate 2 that are adjacentto each other in the bend region. The plurality of discontinuous barrierlayers 4 are spaced apart from each other in a direction K perpendicularto the bending direction L, so that part of lithium ions are not blockedby the barrier layer 4, that is, the part of lithium ions pass betweentwo adjacent barrier layers 4 and are intercalated into the negativeelectrode active material layer of the negative electrode plate 2. Forexample, the plurality of discontinuous barrier layers 4 are attached tothe surface of the positive electrode plate 1. The direction Kperpendicular to the bending direction L may be a width direction of thepositive electrode plate 1 and the negative electrode plate 2. When theelectrode assembly is a winding structure, the direction K perpendicularto the bending direction L is a winding axis direction of the windingstructure.

For still another example, as shown in FIG. 6 , FIG. 6 is a schematicstructural diagram showing another type of distribution of barrierlayers after a bend region of an electrode assembly is flattenedaccording to another embodiment of this application. The barrier layer 4is attached to the surface of the positive electrode plate 1. Thebarrier layer 4 is provided with at least one through hole 41,configured to allow part of lithium ions to pass through and beintercalated into the negative electrode active material layer of thenegative electrode plate 2.

In another embodiment of this application, the porosity of the barrierlayer 4 is less than the porosity of the separator 3, so that thebarrier layer 4 can more effectively block passage of lithium ions. Theporosity is a percentage of a pore volume of bulk material in a totalvolume of the material in a natural state. Generally, a test method forporosity is a test method for true density.

In order to achieve a good balance between blocking lithium ions andmaintaining energy density, the thickness of the barrier layer 4 is Amicron, and the porosity of the barrier layer 4 is B, where A and Bsatisfy the following relationship: 3.5 microns≤A/B≤2000 microns,optionally, 7 microns≤A/B≤1000 microns. This can ensure both safety ofthe electrode assembly and energy density of the electrode assembly,achieving a better balance between safety performance and energydensity. A being excessively small indicates that the thickness of thebarrier layer 4 is excessively small, and lithium crystals are prone topierce the barrier layer 4 or even pierce the separator 3, so that thebarrier layer 4 is unable to block lithium ions, possibly leading to asafety risk. B being excessively large indicates that the porosity ofthe barrier layer 4 is excessively large. A larger porosity of thebarrier layer 4 indicates that more lithium ions pass through thebarrier layer 4, possibly resulting in severe lithium precipitation. Forexample, A/B being less than 3.5 indicates that A is relatively small,that is, the thickness of the barrier layer 4 is excessively small and Bis relatively large. In other words, the porosity of the barrier layer 4is excessively large, and the barrier layer 4 loses the function ofblocking lithium ions, possibly leading to a safety risk. A/B beinggreater than 2000 indicates that A is relatively large, that is, thethickness of the barrier layer 4 is excessively large and B isrelatively small. In other words, the porosity of the barrier layer 4 isexcessively small, which severely affects energy density of the batterycell.

For example, the thickness of the barrier layer 4 is 2 to 200 microns(um); optionally, the thickness of the barrier layer 4 is 5 to 100microns; further optionally, the thickness of the barrier layer 4 is 5to 50 microns. This can ensure both safety of the electrode assembly andenergy density of the electrode assembly, achieving a better balancebetween safety performance and energy density. For example, thethickness of the barrier layer 4 being less than 2 um indicates that thethickness of the barrier layer 4 is excessively small. In case of severelithium precipitation, lithium crystals pierce the barrier layer 4 andeven pierce the separator 3, and consequently the barrier layer 4 isunable to block lithium ions, leading to a safety risk. The thickness ofthe barrier layer 4 being greater than 500 um indicates that thethickness of the barrier layer 4 is excessively large, leading to anexcessively large gap between the positive electrode plate 1 and thenegative electrode plate 2 that are adjacent to each other. The barrierlayer 4 occupies space, which may affect the energy density of theelectrode assembly. In addition, an excessively large gap between twoadjacent layers may severely affect cycle performance.

The porosity of the barrier layer 4 is 10% to 70%; optionally, theporosity of the barrier layer 4 is 20% to 60%. This can ensure bothsafety of the electrode assembly and energy density of the electrodeassembly, achieving a better balance between safety performance andenergy density. For example, when the porosity is less than 10%, most orall of the lithium ions may be blocked by the barrier layer 4, andcannot be intercalated into the negative electrode plate 2, therebyaffecting the energy density of the electrode assembly. However, whenthe porosity is greater than 70%, most or almost all of the lithium ionsmay pass through the barrier layer 4, leading to a risk of lithiumprecipitation. As a result, lithium crystals may pierce the barrierlayer 4, and the barrier layer 4 is unable to block lithium ions,leading to a safety risk.

When the electrode assembly is of a winding structure, the widthdirection of the positive electrode plate 1 and the negative electrodeplate 2 is parallel to the winding axis direction, and the widthdirection of the positive electrode plate 1 and the negative electrodeplate 2 is perpendicular to the bending direction L. When the electrodeassembly is not of a winding structure, the width direction of thepositive electrode plate 1 and the negative electrode plate 2 isparallel to the direction perpendicular to the bending direction L. Forease of subsequent description, in this embodiment, the width directionof the positive electrode plate 1 and the negative electrode plate 2,the direction perpendicular to the bending direction L, and the windingaxis direction are collectively referred to as the direction K.

The structure of the negative electrode plate 2 may be shown in FIG. 7 .FIG. 7 is a schematic structural diagram of a negative electrode plateaccording to another embodiment of this application. The negativeelectrode plate 2 includes a negative electrode body portion 21 and anegative electrode tab 22 extending outwards the negative electrode bodyportion 21 in the direction K. At least a partial region on a surface ofthe negative electrode body portion 21 in the direction K is a negativeelectrode active material region 211. The negative electrode activematerial region 211 is used to coat the negative active material, andthe negative electrode active material may be graphite or silicon.

In another embodiment of this application, the negative electrode activematerial region 211 is not only provided in the partial region on thesurface of the negative electrode body portion 21; the negativeelectrode active material region 211 is also provided on a surface ofthe negative electrode tab 22 and a root region near the negativeelectrode body portion 21, that is, a partial region of the negativeelectrode tab 22 is the negative electrode active material region 211.

In another embodiment of this application, as shown in FIG. 7 , thenegative electrode active material region 211 covers the entire surfaceof the negative electrode body portion 21 in the direction K.

In another embodiment of this application, the positive electrode activematerial may not cover the entire surface of the positive electrodeplate 1. For example, FIG. 8 is a schematic structural diagram of apositive electrode plate according to another embodiment of thisapplication.

The positive electrode plate 1 includes a positive electrode bodyportion 11 and at least one positive electrode tab portion 12 extendingoutwards the positive electrode body portion 11 in the direction K. Atleast a partial region of the surface of the positive electrode bodyportion 11 is a positive electrode active material region 111. Thepositive electrode active material region 111 may be coated with apositive electrode active material, for example, the positive electrodeactive material may be a ternary material, lithium manganate oxide, orlithium iron phosphate.

In another embodiment of this application, the surface of the positiveelectrode body portion 11 further includes a first insulation layercoated region 112 adjacent to the positive electrode active materialregion 111, and the first insulation layer coated region 112 is locatedat a side of the positive electrode active material region 111 adjacentto the positive electrode tab portion 12. The first insulation layercoated region 112 is used for coating with an insulation material, toinsulate and isolate the positive active material region 111 from thepositive electrode tab portion 12. For example, FIG. 9 is a schematicstructural diagram of a cross section in a direction A-A in FIG. 8 . Thepositive electrode active material region 111 is provided on twosurfaces of a current collector 10 of the positive electrode plate 1,and the positive electrode tab portion 12 is a part of the currentcollector 10 of the positive electrode plate 1. The current collector 10may be made of aluminum.

For example, the positive electrode active material region 111 and thefirst insulation layer coated region 112 are distributed at two ends, inthe width direction (the direction K) of the positive electrode bodyportion 11, of the surface of the positive electrode body portion 11,and the positive electrode tab portion 12 and the first insulation layercoated region 112 belongs to the same end of the positive electrode bodyportion 11.

In another embodiment of this application, the positive electrode activematerial region 111 and the first insulation layer coated region 112 aretwo substantially parallel regions on the surface of the positiveelectrode body portion 11, and are distributed as two layers on thesurface of the positive electrode body portion 11 in the direction K.

In another embodiment of this application, the first insulation layercoated region 112 may be located at a joint portion between the positiveelectrode body portion 11 and the positive electrode tab portion 12. Forexample, the first insulation layer coated region 112 is located on thesurface of the positive electrode body portion 11 and the joint portionbetween the positive electrode body portion 11 and the positiveelectrode tab portion 12, and is used to isolate the surface of thepositive electrode tab portion 12 from the positive electrode activematerial region 111. In another embodiment of this application, thefirst insulation layer coated region 112 is provided on the surface ofthe positive electrode body portion 11, and a second insulation layercoated region is also provided in the root region of the positiveelectrode tab portion 12 close to the positive electrode body portion11. The second insulation layer coated region are used for coating of aninsulation material.

In another embodiment of this application, an insulation material iscoated to the surface of the first insulation layer coated region 112,and the insulation material includes an inorganic filler and a binder.The inorganic filler includes one or more of boehmite, aluminum oxide,magnesium oxide, titanium dioxide, zirconium oxide, silicon dioxide,silicon carbide, boron carbide, calcium carbonate, aluminum silicate,calcium silicate, potassium titanate, and barium sulfate. The binderincludes one or more of polyvinylidene fluoride, polyacrylonitrile,polyacrylic acid, polyacrylate, polyacrylic acid-acrylate,polyacrylonitrile-acrylic acid, and polyacrylonitrile-acrylate.

In another embodiment of this application, each positive electrode plate1 may include one, two, or more than two positive electrode tab portions12. When the positive electrode plate 1 includes two or more positivetab portions 12, all the positive pole tab portions 12 are located onthe same side of the positive electrode plate 1 in the direction K.

With reference to FIG. 7 and FIG. 8 , when the positive electrode plate1 and the negative electrode plate 2 are stacked, two ends of thenegative electrode active material region 211 of the negative electrodeplate 2 in the direction K extend beyond corresponding ends of thepositive electrode active material region 111 of the adjacent positiveelectrode plate 1. This can ensure the energy density of the electrodeassembly. For example, the two ends of the negative electrode activematerial region 211 in the direction K are a first end 23 and a secondend 24, and the two ends of the positive electrode active materialregion 111 in the direction K are a third end 13 and a fourth end 14.The first end 23 of the negative electrode active material region 211and the third end 13 of the positive electrode active material region111 are located on the same side of the electrode assembly in thedirection K, and the first end 23 of the negative electrode activematerial region 211 extends beyond the third end 13 of the positiveelectrode active material region 111 in the direction K. The second end24 of the negative electrode active material region 211 and the fourthend 14 of the positive electrode active material region 111 are locatedon the other side of the electrode assembly in the direction K, and thesecond end 24 of the negative electrode active material region 211extends beyond the fourth end 14 of the positive electrode activematerial region 111 in the direction K.

A size by which the two ends of the negative electrode active materialregion 211 extending beyond the corresponding ends of the positiveelectrode active material region 111 along the winding axis K may be thesame or different. For example, an exceeding size ranges from 0.2 mm to5 mm.

As shown in FIG. 10 , FIG. 10 is a schematic structural diagram of across section in a direction B-B in FIG. 8 . With reference to FIG. 8 ,the barrier layer 4 is attached to the surface of the positive electrodeactive material region 111, that is, the surface of the positiveelectrode active material layer.

In order to block lithium ions and reduce costs, the barrier layer 4includes a fifth end 42 and a sixth end 43 in the directionperpendicular to the bending direction (which is the direction K), andthe fifth end 42 of the barrier layer 4 extends beyond the positiveelectrode active material layer of the positive electrode plate 1,and/or the sixth end 43 of the barrier layer 4 exceeds beyond thepositive electrode active material layer. To be specific, the fifth end42 of the barrier layer 4 exceeds the third end 13 of the positiveelectrode active material region 111 in the direction K, and/or thesixth end 43 of the barrier layer 4 extends beyond the fourth end 14 ofthe positive electrode active material region 111 in the direction K,for example, the exceeding size ranges from 0.2 mm to 5 mm. In this way,passage of more lithium ions can be blocked, reducing lithiumprecipitation.

In another embodiment of this application, both the fifth end 42 and thesixth end 43 of the barrier layer 4 do not exceed the corresponding endsof the negative electrode active material layer of the negativeelectrode plate 2. That is, the first end 23 of the negative electrodeactive material region of the negative electrode plate 2 extends beyondthe fifth end 42 of the barrier layer 4, and/or the second end 24 of thenegative electrode active material region of the negative electrodeplate 2 extends beyond the sixth end 43 of the barrier layer 4. In thisway, lithium ions can be intercalated into a portion of the negativeelectrode plate 2 extending beyond the barrier layer 4, ensuring theenergy density of the electrode assembly.

The foregoing embodiments briefly describe only a positionalrelationship between the barrier layer and the positive electrode plate,a positional relationship between the barrier layer and the negativeelectrode plate, and a structural characteristic of the barrier layer.For better understanding on the positional relationship between thebarrier layer and the positive electrode plate, the positionalrelationship between the barrier layer and the negative electrode plate,and the structure of the barrier layer, the following describes indetail several electrode assemblies with a winding structure.

As shown in FIG. 11 , FIG. 11 is a schematic structural diagram of across section perpendicular to a winding axis of a flat-shaped electrodeassembly according to another embodiment of this application. Theelectrode assembly includes a negative electrode plate 91, a positiveelectrode plate 92, a separator 93, a first barrier layer 94, a secondbarrier layer 95, and a third barrier layer 96. The separator 93 islocated between the negative electrode plate 91 and the positiveelectrode plate 92, and there are two separators 93, indicated by twowinding dashed lines in the cross-sectional view of the electrodeassembly in FIG. 11 . The negative electrode plate 91, the positiveelectrode plate 92, and the separator 93 are stacked and then wound intoa flat-shaped winding structure around the winding axis.

For related technical features of the negative electrode plate 91, thepositive electrode plate 92, and the separator 93 in this embodiment,refer to the descriptions of the embodiments corresponding to FIGS. 1 to10 . Details are not repeated herein.

In this embodiment, the winding structure of the electrode assemblyincludes a flat region 9A, and a first bend region 9B1 and a second bendregion 9B2 that are located on two sides of the flat region 9A. Divisionof the flat region 9A from the first bend region 9B1 and the second bendregion 9B2 is separately denoted by a straight dotted line.

The negative electrode plate 91 and the positive electrode plate 92included in the first bend region 9B1 and the second bend region 9B2 ofthe electrode assembly are alternately stacked in sequence. Theseparator 93 is provided between the negative electrode plate 91 and thepositive electrode plate 92 that are adjacent to each other. Innermostelectrode plates in the first bend region 9B1 and the second bend region9B2 are both the negative electrode plate 91. A barrier layer isprovided (attached to) on inner surfaces of at least innermost positiveelectrode plates 92 in the first bend region 9B1 and the second bendregion 9B2. For example, a barrier layer is provided (attached to) on aninner surface of each layer of positive electrode plate 92 in the firstbend region 9B1 and the second bend region 9B2. In this embodiment, theinner surface of the positive electrode plate 92 is a surface of thepositive electrode plate 92 facing toward the winding axis, or a surfacefacing toward inside of the winding structure.

For example, the first bend region 9B1 has a plurality of layers ofelectrode plates, such as three layers of electrode plates. Aninnermost-layer electrode plate (also referred to as the first layer)and an outermost-layer electrode plate (also referred to as the thirdlayer) of the first bend region 9B1 are both the negative electrodeplate 91, and an electrode plate (also referred to as the second-layerelectrode plate) between the innermost-layer electrode plate and theoutermost-layer electrode plate is the positive electrode plate 92. Thepositive electrode plate 92 is a positive electrode plate on theinnermost side of the first bend region 9B1, and the first barrier layer94 is attached to an inner surface of the positive electrode plate 92 inthe first bend region 9B1.

The second bend region 9B2 has a plurality of layers of electrodeplates, such as five layers of electrode plates. In a direction frominside to outside of the winding structure, the negative electrode plate91 and the positive electrode plate 92 in the second bend region 9B2 arealternately stacked in sequence. An innermost-layer electrode plate inthe second bend region 9B2 is the negative electrode plate 91, and abarrier layer is attached to an inner surface of each layer of positiveelectrode plate 92 in the second bend region 9B2.

For example, in the direction from inside to outside of the windingstructure, the second bend region 9B2 sequentially includes thefirst-layer, second-layer, third-layer, fourth-layer, and fifth-layerelectrode plates. The first-layer, third-layer, and fifth-layerelectrode plates are the negative electrode plate 91; and thesecond-layer and fourth-layer electrode plates are the positiveelectrode plate 92. A barrier layer is attached to the inner surface ofeach layer of layer of positive electrode plate 92 in the second bendregion 9B2. For example, the second barrier layer 95 is attached to aninner surface of the second-layer electrode plate (which is the positiveelectrode plate 92) in the second bend region 9B2. For example, thethird barrier layer 96 is attached to an inner surface of thefourth-layer electrode plate (which is the positive electrode plate 92)in the second bend region 9B2.

In this embodiment, two ends of each of the first barrier layer 94, thesecond barrier layer 95, and the third barrier layer 96 in the bendingdirection (that is, in the winding direction) are located at thejunctions between the bend region and the flat region. For example, twoends of the first barrier layer 94 in the winding direction areseparately located at the junction between the first bend region 9B1 andthe flat region 9A, and two ends of each of the second barrier layer 95and the third barrier layer 96 in the winding direction are separatelylocated at the junction between the second bend region 9B2 and the flatregion 9A.

In this embodiment, for related content of functions, structures, anddistribution of the first barrier layer 94, the second barrier layer 95,and the third barrier layer 96, refer to related content of the barrierlayer described in the embodiments of FIGS. 1 to 10 . Details are notrepeated herein.

As shown in FIG. 12 , FIG. 12 is a schematic structural diagram of across section perpendicular to a winding axis of another flat-shapedelectrode assembly according to another embodiment of this application.The electrode assembly includes a negative electrode plate 1001, apositive electrode plate 1002, a separator 1003, a first barrier layer1004, a second barrier layer 1005, and a third barrier layer 1006. Theseparator 1003 is located between the negative electrode plate 1001 andthe positive electrode plate 1002. The negative electrode plate 1001,the positive electrode plate 1002, and the separator 1003 are stackedand then wound into a flat-shaped winding structure around the windingaxis.

For related technical features of the negative electrode plate 1001, thepositive electrode plate 1002, and the separator 1003 in thisembodiment, refer to the descriptions of the embodiments correspondingto FIGS. 1 to 10 . Details are not repeated herein.

In this embodiment, the winding structure of the electrode assemblyincludes a flat region 10A, and a first bend region 10B1 and a secondbend region 10B2 that are located on two sides of the flat region 10A.

The electrode assembly in this embodiment is basically similar to theelectrode assembly described in the embodiment corresponding to FIG. 11, and the difference may be as follows:

A barrier layer is provided (attached to) on outer surfaces of at leastinnermost positive electrode plates 1002 in the first bend region 10B1and the second bend region 10B2. For example, a barrier layer isprovided (attached to) on an outer surface of each layer of positiveelectrode plate 1002 in the first bend region 10B1 and the second bendregion 10B2. In this embodiment, the outer surface of the positiveelectrode plate 1002 is a surface of the positive electrode plate 1002facing away from the winding axis, or a surface facing away from insideof the winding structure.

For example, the first barrier layer 1004 is attached to an outersurface of the positive electrode plate 1002 in the first bend region10B1.

For example, the second barrier layer 1005 is attached to an outersurface of the second-layer electrode plate (which is the positiveelectrode plate 1002) in the second bend region 10B2. For example, athird barrier layer 1006 is attached to an outer surface of thefourth-layer electrode plate (which is the positive electrode plate1002) in the second bend region 10B2.

In this embodiment, two ends of the first barrier layer 1004 in thewinding direction are located at the junctions between the first bendregion 10B1 and the flat region 10A, and two ends of each of the secondbarrier layer 1005 and the third barrier layer 1006 in the windingdirection are located at the junctions between the second bend region10B2 and the flat region 10A.

In this embodiment, for related content of functions, structures, anddistribution of the first barrier layer 1004, the second barrier layer1005, and the third barrier layer 1006, refer to related content of thebarrier layer described in the embodiments of FIGS. 1 to 10 . Detailsare not repeated herein.

As shown in FIG. 13 , FIG. 13 is a schematic structural diagram of across section perpendicular to a winding axis of another flat-shapedelectrode assembly according to another embodiment of this application.The electrode assembly includes a negative electrode plate 1101, apositive electrode plate 1102, a separator 1103, a first barrier layer1104, a second barrier layer 1105, a third barrier layer 1106, a fourthbarrier layer 1107, and a fifth barrier layer 1108. The separator 1103is located between the negative electrode plate 1101 and the positiveelectrode plate 1102. The negative electrode plate 1101, the positiveelectrode plate 1102, and the separator 1103 are stacked and then woundinto a flat-shaped winding structure around the winding axis.

For related technical features of the negative electrode plate 1101, thepositive electrode plate 1102, and the separator 1103 in thisembodiment, refer to the descriptions of the embodiments correspondingto FIGS. 1 to 10 . Details are not repeated herein.

In this embodiment, the winding structure of the electrode assemblyincludes a flat region 11A, and a first bend region 11B1 and a secondbend region 11B2 that are located on two sides of the flat region 11A.

The electrode assembly in this embodiment is basically similar to theelectrode assembly described in the embodiment corresponding to FIG. 11, and the difference may be as follows:

A barrier layer is provided (attached to) on inner surfaces of at leastinnermost negative electrode plates 1101 in a first bend region 11B1 anda second bend region 11B2. For example, a barrier layer is provided onan inner surface of each layer of negative electrode plate 1101 in thefirst bend region 11B1 and the second bend region 11B2. In thisembodiment, the inner surface of the negative electrode plate 1101 is asurface of the negative electrode plate 1101 facing toward the windingaxis, or a surface facing toward inside of the winding structure.

For example, the first barrier layer 1104 is attached to an innersurface of an innermost-layer electrode plate (which is the negativeelectrode plate 1101) in the first bend region 11B1, and the secondbarrier layer 1105 is attached to an inner surface of an outermost-layerelectrode plate (which is the negative electrode plate 1101).

For example, the third barrier layer 1106 is attached to an innersurface of the first-layer electrode plate (which is the negativeelectrode plate 1101) in the second bend region 11B2. The fourth barrierlayer 1107 is attached to an inner surface of the third-layer electrodeplate (which is the negative electrode plate 1101) in the second bendregion 11B2. The fifth barrier layer 1108 is attached to an innersurface of the fifth-layer electrode plate (which is the negativeelectrode plate 1101) in the second bend region 11B2.

In this embodiment, two ends of each of the first barrier layer 1104 andthe second barrier layer 1105 in the winding direction are located atthe junctions between the first bend region 11B1 and the flat region11A, and two ends of each of the third barrier layer 1106, the fourthbarrier layer 1107, and the fifth barrier layer 1108 in the windingdirection are located at the junctions between the second bend region11B2 and the flat region 11A.

In this embodiment, for related content of functions, structures, anddistribution of the first barrier layer 1104, the second barrier layer1105, and the third barrier layer 1106, the fourth barrier layer 1107,and the fifth barrier layer 1108, refer to related content of thebarrier layer described in the embodiments of FIGS. 1 to 10 . Detailsare not repeated herein.

As shown in FIG. 14 , FIG. 14 is a schematic structural diagram of across section perpendicular to a winding axis of another flat-shapedelectrode assembly according to another embodiment of this application.The electrode assembly includes a negative electrode plate 1201, apositive electrode plate 1202, a separator 1203, a first barrier layer1204, a second barrier layer 1205, a third barrier layer 1206, a fourthbarrier layer 1207, and a fifth barrier layer 1208. The separator 1203is located between the negative electrode plate 1201 and the positiveelectrode plate 1202. The negative electrode plate 1201, the positiveelectrode plate 1202, and the separator 1203 are stacked and then woundinto a flat-shaped winding structure around the winding axis.

For related technical features of the negative electrode plate 1201, thepositive electrode plate 1202, and the separator 1203 in thisembodiment, refer to the descriptions of the embodiments correspondingto FIGS. 1 to 10 . Details are not repeated herein.

In this embodiment, the winding structure of the electrode assemblyincludes a flat region 12A, and a first bend region 12B1 and a secondbend region 12B2 that are located on two sides of the flat region 12A.

The electrode assembly in this embodiment is basically similar to theelectrode assembly described in the embodiment corresponding to FIG. 11, and the difference may be as follows:

A barrier layer is provided (attached to) on outer surfaces of at leastinnermost negative electrode plates 1201 in the first bend region 12B1and the second bend region 12B2. For example, a barrier layer isprovided on an outer surface of each layer of negative electrode plate1201 in the first bend region 12B1 and the second bend region 12B2. Inthis embodiment, the outer surface of the negative electrode plate 1201is a surface of the negative electrode plate 1201 facing away from thewinding axis, or a surface facing away from inside of the windingstructure.

For example, the first barrier layer 1204 is attached to an outersurface of an innermost-layer electrode plate (which is the negativeelectrode plate 1201) in the first bend region 12B1, and the secondbarrier layer 1205 is attached to an outer surface of an outermost-layerelectrode plate (which is the negative electrode plate 1201).

For example, the third barrier layer 1206 is attached to an outersurface of the first-layer electrode plate (which is the negativeelectrode plate 1201) in the second bend region 12B2. The fourth barrierlayer 1207 is attached to an outer surface of the third-layer electrodeplate (which is the negative electrode plate 1201) in the second bendregion 12B2. The fifth barrier layer 1208 is attached to an outersurface of the fifth-layer electrode plate (which is the negativeelectrode plate 1201) in the second bend region 12B2.

In this embodiment, two ends of each of the first barrier layer 1204 andthe second barrier layer 1205 in the winding direction are located atthe junctions between the first bend region 12B1 and the flat region12A, and two ends of each of the third barrier layer 1206, the fourthbarrier layer 1207, and the fifth barrier layer 1208 in the windingdirection are located at the junctions between the second bend region12B2 and the flat region 12A.

In this embodiment, for related content of functions, structures, anddistribution of the first barrier layer 1204, the second barrier layer1205, and the third barrier layer 1206, the fourth barrier layer 1207,and the fifth barrier layer 1208, refer to related content of thebarrier layer described in the embodiments of FIGS. 1 to 10 . Detailsare not repeated herein.

As shown in FIG. 15 , FIG. 15 is a schematic structural diagram of across section perpendicular to a winding axis of another flat-shapedelectrode assembly according to another embodiment of this application.The electrode assembly includes a negative electrode plate 1301, apositive electrode plate 1302, a separator 1303, and a plurality ofbarrier layers 1304. The separator 1303 is located between the negativeelectrode plate 1301 and the positive electrode plate 1302. The negativeelectrode plate 1301, the positive electrode plate 1302, and theseparator 1303 are stacked and then wound into a flat-shaped windingstructure around the winding axis.

For related technical features of the negative electrode plate 1301, thepositive electrode plate 1302, and the separator 1303 in thisembodiment, refer to the descriptions of the embodiments correspondingto FIGS. 1 to 10 . Details are not repeated herein.

In this embodiment, the winding structure of the electrode assemblyincludes a flat region 13A, and a first bend region 13B1 and a secondbend region 13B2 that are located on two sides of the flat region 13A.

The electrode assembly in this embodiment is basically similar to theelectrode assembly described in the embodiment corresponding to FIG. 11, and the difference may be as follows:

The barrier layer 1304 is provided on inner surfaces of at leastinnermost separators 1303 in the first bend region 13B1 and the secondbend region 13B2. For example, the barrier layer 1304 is provided on aninner surface of each layer of separator 1303 in the first bend region13B1 and the second bend region 13B2. In this embodiment, the innersurface of the separator 1303 is a surface of the separator 1303 facingtoward the winding axis, or a surface facing toward inside of thewinding structure.

In this embodiment, two ends of each barrier layer 1304 in the windingdirection in the first bend region 13B1 are located at the junctionsbetween the first bend region 13B1 and the flat region 13A, and two endsof each barrier layer 1304 in the winding direction in the second bendregion 13B2 are located at the junctions between the second bend region13B2 and the flat region 13A.

In this embodiment, for related content of functions, structures, anddistribution of each barrier layer 1304, refer to related content of thebarrier layer described in the embodiments of FIGS. 1 to 10 . Detailsare not repeated herein.

As shown in FIG. 16 , FIG. 16 is a schematic structural diagram of across section perpendicular to a winding axis of another flat-shapedelectrode assembly according to another embodiment of this application.The electrode assembly includes a negative electrode plate 1401, apositive electrode plate 1402, a separator 1403, and a plurality ofbarrier layers 1404. The separator 1403 is located between the negativeelectrode plate 1401 and the positive electrode plate 1402. The negativeelectrode plate 1401, the positive electrode plate 1402, and theseparator 1403 are stacked and then wound into a flat-shaped windingstructure around the winding axis.

For related technical features of the negative electrode plate 1401, thepositive electrode plate 1402, and the separator 1403 in thisembodiment, refer to the descriptions of the embodiments correspondingto FIGS. 1 to 10 . Details are not repeated herein.

In this embodiment, the winding structure of the electrode assemblyincludes a flat region 14A, and a first bend region 14B1 and a secondbend region 14B2 that are located on two sides of the flat region 14A.

The electrode assembly in this embodiment is basically similar to theelectrode assembly described in the embodiment corresponding to FIG. 11, and the difference may be as follows:

The barrier layer 1404 is provided on outer surfaces of at leastinnermost separators 1403 in the first bend region 14B1 and the secondbend region 14B2. For example, the barrier layer 1404 is provided on anouter surface of each layer of separator 1403 in the first bend region14B1 and the second bend region 14B2. In this embodiment, the outersurface of the separator 1403 is a surface of the separator 1403 facingaway from the winding axis, or a surface facing away from inside of thewinding structure.

In this embodiment, two ends of each barrier layer 1404 in the windingdirection in the first bend region 14B1 are located at the junctionsbetween the first bend region 14B1 and the flat region 14A, and two endsof each barrier layer 1404 in the winding direction in the second bendregion 14B2 are located at the junctions between the second bend region14B2 and the flat region 14A.

In this embodiment, for related content of functions, structures, anddistribution of each barrier layer 1404, refer to related content of thebarrier layer described in the embodiments of FIGS. 1 to 10 . Detailsare not repeated herein.

As shown in FIG. 17 , FIG. 17 is a schematic structural diagram of across section perpendicular to a winding axis of another flat-shapedelectrode assembly according to another embodiment of this application.The electrode assembly includes a negative electrode plate 1501, apositive electrode plate 1502, a separator 1503, and a plurality ofbarrier layers 1504. The separator 1503 is located between the negativeelectrode plate 1501 and the positive electrode plate 1502. The negativeelectrode plate 1501, the positive electrode plate 1502, and theseparator 1503 are stacked and then wound into a flat-shaped windingstructure around the winding axis.

For related technical features of the negative electrode plate 1501, thepositive electrode plate 1502, and the separator 1503 in thisembodiment, refer to the descriptions of the embodiments correspondingto FIGS. 1 to 10 . Details are not repeated herein.

In this embodiment, the winding structure of the electrode assemblyincludes a flat region 15A, and a first bend region 15B1 and a secondbend region 15B2 that are located on two sides of the flat region 15A.

The negative electrode plate 1501 and the positive electrode plate 1502that are included in the first bend region 15B1 and the second bendregion 15B2 of the electrode assembly are alternately stacked insequence, and the separator 1503 is provided between any negativeelectrode plate 1501 and positive electrode plate 1502 that are adjacentto each other in the first bend region 15B1 and the second bend region15B2. Innermost electrode plates in the first bend region 15B1 and thesecond bend region 15B2 are all negative electrode plates 1501. Thebarrier layer 1504 is provided on both inner and outer surfaces of atleast the innermost positive electrode plates 1502 in the first bendregion 15B1 and the second bend region 15B2, for example, the barrierlayer 1504 is provided on both inner and outer surfaces of each layer ofpositive electrode plate 1502 in the first bend region 15B1 and thesecond bend region 15B2. In this embodiment, the inner surface of thepositive electrode plate 1502 is a surface of the positive electrodeplate 1502 facing toward the winding axis, or a surface facing towardinside of the winding structure. The outer surface of the positiveelectrode plate 1502 is a surface of the positive electrode plate 1502facing away from the winding axis, or a surface facing away from insideof the winding structure.

For example, the first bend region 15B1 has a plurality of layers ofelectrode plates, such as three layers of electrode plates. Theinnermost-layer (also referred to as first-layer) electrode plate andthe outermost-layer (also referred to as third-layer) electrode plate inthe first bend region 15B1 are both the negative electrode plate 1501.An electrode plate (also referred to as the second-layer electrodeplate) between the innermost-layer electrode plate and theoutermost-layer electrode plate in the first bend region 15B1 is thepositive electrode plate 1502. The barrier layer 1504 is provided(attached to) on both an inner surface and an outer surface of thepositive electrode plate 1502 in the first bend region 15B1.

The second bend region 15B2 has a plurality of layers of electrodeplates, such as five layers of electrode plates. In a direction frominside to outside of the winding structure, the negative electrode plate1501 and the positive electrode plate 1502 in the second bend region15B2 are alternately stacked in sequence. An innermost-layer electrodeplate in the second bend region 15B2 is the negative electrode plate1501, and the barrier layer 1504 is provided (attached to) on both aninner surface and an outer surface of each layer of positive electrodeplate 1502 in the second bend region 15B2.

For example, in the direction from inside to outside of the windingstructure, the second bend region 15B2 sequentially includes thefirst-layer, second-layer, third-layer, fourth-layer, and fifth-layerelectrode plates. The first-layer, third-layer, and fifth-layerelectrode plates are the negative electrode plate 1501; and thesecond-layer and fourth-layer electrode plates are the positiveelectrode plate 1502. The barrier layer 1504 is provided on both innersurfaces and outer surfaces of the second-layer and fourth-layerelectrode plates in the second bend region 15B2.

In this embodiment, two ends of each barrier layer 1504 in the bendingdirection (that is, in the winding direction) are located at thejunctions between the bend region and the flat region. For example, twoends of each barrier layer 1504 in the first bend region 15B1 in thewinding direction are located at the junctions between the first bendregion 15B1 and the flat region 15A, and two ends of each barrier layer1504 in the second bend region 15B2 in the winding direction are locatedat the junctions between the second bend region 15B2 and the flat region15A.

In this embodiment, for related content of functions, structures, anddistribution of each barrier layer 1504, refer to related content of thebarrier layer described in the embodiments of FIGS. 1 to 10 . Detailsare not repeated herein.

As shown in FIG. 18 , FIG. 18 is a schematic structural diagram of across section perpendicular to a winding axis of a flat-shaped electrodeassembly according to another embodiment of this application. Theelectrode assembly includes a negative electrode plate 1601, a positiveelectrode plate 1602, a separator 1603, a first barrier layer 1604, asecond barrier layer 1605, and a third barrier layer 1606. The separator1603 is located between the negative electrode plate 1601 and thepositive electrode plate 1602. The negative electrode plate 1601, thepositive electrode plate 1602 and the separator 1603 are stacked andthen wound into a flat-shaped winding structure around the winding axis.

For related technical features of the negative electrode plate 1601, thepositive electrode plate 1602, and the separator 1603 in thisembodiment, refer to the descriptions of the embodiments correspondingto FIGS. 1 to 10 . Details are not repeated herein.

In this embodiment, the winding structure of the electrode assemblyincludes a first flat region 16A1, a second flat region 16A2, a firstbend region 16B1, and a second bend region 16B2. The first flat region16A1 and the second flat region 16A2 are disposed opposite each other.The first bend region 16B1 and the second bend region 16B2 are disposedopposite each other. Two ends of the first bend region 16B1 arerespectively connected to ends of the first flat region 16A1 and thesecond flat region 16A2 on the same side. Two ends of the second bendregion 16B2 are respectively connected to the other ends of the firstflat region 16A1 and the second flat region 16A2 on the same side.

The negative electrode plate 1601 and the positive electrode plate 1602included in the first bend region 16B1 and the second bend region 16B2of the electrode assembly are alternately stacked in sequence. Theseparator 1603 is provided between the negative electrode plate 1601 andthe positive electrode plate 1602 that are adjacent to each other.Innermost electrode plates in the first bend region 16B1 and the secondbend region 16B2 are both negative electrode plates 1601. A barrierlayer is provided (attached to) on inner surfaces of at least innermostpositive electrode plates in the first bend region 16B1 and the secondbend region 16B2. For example, a barrier layer is provided (attached to)on an inner surface of each layer of positive electrode plate 1602 inthe first bend region 16B1 and the second bend region 16B2. In thisembodiment, the inner surface of the positive electrode plate 1602 is asurface of the positive electrode plate 1602 facing toward the windingaxis, or a surface facing toward inside of the winding structure.

For example, the first bend region 16B1 has a plurality of layers ofelectrode plates, such as three layers of electrode plates. Theinnermost-layer (also referred to as first-layer) electrode plate andthe outermost-layer (also referred to as third-layer) electrode plate inthe first bend region 16B1 are both the negative electrode plate 1601.An electrode plate (also referred to as the second-layer electrodeplate) between the innermost-layer electrode plate and theoutermost-layer electrode plate is the positive electrode plate 1602.The first barrier layer 1604 is attached to an inner surface of thepositive electrode plate 1602 in the first bend region 16B1.

For example, the second bend region 16B2 has a plurality of layers ofelectrode plates, such as five layers of electrode plates. In adirection from inside to outside of the winding structure, the negativeelectrode plate 1601 and the positive electrode plate 1602 in the secondbend region 16B2 are alternately stacked in sequence. An innermost-layerelectrode plate in the second bend region 16B2 is the negative electrodeplate 1601, and a barrier layer is attached to an inner surface of eachlayer of positive electrode plate 1602 in the second bend region 16B2.

For example, in the direction from inside to outside of the windingstructure, the second bend region 16B2 sequentially includes thefirst-layer, second-layer, third-layer, fourth-layer, and fifth-layerelectrode plates. The first-layer, third-layer, and fifth-layerelectrode plates are the negative electrode plate 1601; and thesecond-layer and fourth-layer electrode plates are the positiveelectrode plate 1602. The second barrier layer 1605 is attached to aninner surface of the positive electrode plate 1602 in the negativeelectrode plate 1601 and the positive electrode plate 1602 that areadjacent to each other on the innermost side of the second bend region16B2, that is, the second barrier layer 1605 is attached to an innersurface of the second-layer electrode plate (which is the positiveelectrode plate 1602) in the second bend region 16B2. For example, thethird barrier layer 1606 is attached to an inner surface of thefourth-layer electrode plate (which is the positive electrode plate1602) in the second bend region 16B2.

In this embodiment, the first barrier layer 1604 includes a first endand a second end in the bending direction (that is, in the windingdirection). The first end of the first barrier layer 1604 is located inthe first bend region 16B1, and the second end of the layer 1604 islocated in the first flat region 16A1. The second barrier layer 1605includes a first end and a second end in the bending direction (that is,in the winding direction). The first end of the second barrier layer1605 is located in the second bend region 16B2, and the second end ofthe second barrier layer 1605 is located in the second flat region 16A2.The third barrier layer 1606 includes a first end and a second end inthe bending direction (that is, in the winding direction). The first endof the third barrier layer 1606 is located in the second bend region16B2, and the second end of the third barrier layer 1606 is located inthe second flat region 16A2. In another embodiment of this application,the first end of the third barrier layer 1606 is located in the secondbend region 16B2, and the second end of the third barrier layer 1606 islocated in the first flat region 16A1.

In this embodiment, for related content of functions, structures, anddistribution of the first barrier layer 1604, the second barrier layer1605, and the third barrier layer 1606, refer to related content of thebarrier layer described in the embodiments of FIGS. 1 to 10 . Detailsare not repeated herein.

As shown in FIG. 19 , FIG. 19 is a schematic structural diagram of across section perpendicular to a winding axis of a flat-shaped electrodeassembly according to another embodiment of this application. Theelectrode assembly includes a negative electrode plate 1701, a positiveelectrode plate 1702, a separator 1703, a first barrier layer 1704, asecond barrier layer 1705, and a third barrier layer 1706. The separator1703 is located between the negative electrode plate 1701 and thepositive electrode plate 1702. The negative electrode plate 1701, thepositive electrode plate 1702, and the separator 1703 are stacked andthen wound into a flat-shaped winding structure around the winding axis.

For related technical features of the negative electrode plate 1701, thepositive electrode plate 1702, and the separator 1703 in thisembodiment, refer to the descriptions of the embodiments correspondingto FIGS. 1 to 10 . Details are not repeated herein.

In this embodiment, the winding structure of the electrode assemblyincludes a first flat region 17A1, a second flat region 17A2, a firstbend region 17B1, and a second bend region 17B2. The first flat region17A1 and the second flat region 17A2 are disposed opposite each other.The first bend region 17B1 and the second bend region 17B2 are disposedopposite each other. Two ends of the first bend region 17B1 arerespectively connected to ends of the first flat region 17A1 and thesecond flat region 17A2 on the same side. Two ends of the second bendregion 17B2 are respectively connected to the other ends of the firstflat region 17A1 and the second flat region 17A2 on the same side.

The negative electrode plate 1701 and the positive electrode plate 1702included in the first bend region 17B1 and the second bend region 17B2of the electrode assembly are alternately stacked in sequence. Theseparator 1703 is provided between the negative electrode plate 1701 andthe positive electrode plate 1702 that are adjacent to each other.Innermost electrode plates in the first bend region 17B1 and the secondbend region 17B2 are both negative electrode plates 1701. A barrierlayer is provided (attached to) on inner surfaces of at least innermostpositive electrode plates 1702 in the first bend region 17B1 and thesecond bend region 17B2. For example, a barrier layer is provided(attached to) on an inner surface of each layer of positive electrodeplate 1702 in the first bend region 17B1 and the second bend region17B2. In this embodiment, the inner surface of the positive electrodeplate 1702 is a surface of the positive electrode plate 1702 facingtoward the winding axis, or a surface facing toward inside of thewinding structure.

For example, the first bend region 17B1 has a plurality of layers ofelectrode plates, such as three layers of electrode plates. Theinnermost-layer (also referred to as first-layer) electrode plate andthe outermost-layer (also referred to as third-layer) electrode plate inthe first bend region 17B1 are both the negative electrode plate 1701.An electrode plate (also referred to as the second-layer electrodeplate) between the innermost-layer electrode plate and theoutermost-layer electrode plate is the positive electrode plate 1702.The first barrier layer 1704 is attached to an inner surface of thepositive electrode plate 1702 in the first bend region 17B1.

The second bend region 17B2 is provided with a plurality of layers ofelectrode plates, such as five layers of electrode plates. In adirection from inside to outside of the winding structure, the negativeelectrode plate 1701 and the positive electrode plate 1702 in the secondbend region 17B2 are alternately stacked in sequence. An innermost-layerelectrode plate in the second bend region 17B2 is the negative electrodeplate 1701, and a barrier layer is attached to an inner surface of eachlayer of positive electrode plate 1702 in the second bend region 17B2.

For example, in the direction from inside to outside of the windingstructure, the second bend region 17B2 sequentially includes thefirst-layer, second-layer, third-layer, fourth-layer, and fifth-layerelectrode plates. The first-layer, third-layer, and fifth-layerelectrode plates are the negative electrode plate 1701; and thesecond-layer and fourth-layer electrode plates are the positiveelectrode plate 1702. The second barrier layer 1705 is attached to aninner surface of the positive electrode plate 1702 in the negativeelectrode plate 1701 and the positive electrode plate 1702 that areadjacent to each other on the innermost side of the second bend region17B2, that is, the second barrier layer 1705 is attached to an innersurface of the second-layer electrode plate (which is the positiveelectrode plate 1702) in the second bend region 17B2. For example, thethird barrier layer 1706 is attached to an inner surface of thefourth-layer electrode plate (which is the positive electrode plate1702) in the second bend region 17B2.

In this embodiment, the first barrier layer 1704 includes a first endand a second end in the bending direction (that is, in the windingdirection), and the first end and the second end of the first barrierlayer 1704 are both located in the first bend region 17B1. The secondbarrier layer 1705 includes a first end and a second end in the bendingdirection (that is, in the winding direction). The first end of thesecond barrier layer 1705 is located at a junction between the secondbend region 17B2 and the first flat region 17A1, and the second end ofthe second barrier layer 1705 is located at a junction between thesecond bend region 17B2 and the second flat region 17A2. The thirdbarrier layer 1706 includes a first end and a second end in the bendingdirection (that is, in the winding direction), and the first end and thesecond end of the third barrier layer 1706 are both located in thesecond bend region 17B2.

In this embodiment, in the second bend region 17B2, in a directionperpendicular to the winding axis from inside to outside of theelectrode assembly, curvatures of the layers of electrode platesdecrease sequentially, that is, a bending degree decreases gradually. Inthe direction perpendicular to the winding axis from inside to outsideof the electrode assembly, circumferential angles covered by barrierlayers in the second bend region 17B2 in the winding direction decreasesequentially. For example, a circumferential angle covered by the thirdbarrier layer 1706 in the second bend region 17B2 in the windingdirection is less than a circumferential angle covered by the secondbarrier layer 1705 in the second bend region 17B2. For example, thecircumference angle covered by the third barrier layer 1706 in thesecond bend region 17B2 in the winding direction is 90°, and thecircumferential angle covered by the second barrier layer 1705 in thesecond bend region 17B2 in the winding direction is 180°.

In this embodiment, for related content of functions, structures, anddistribution of the first barrier layer 1704, the second barrier layer1705, and the third barrier layer 1706, refer to related content of thebarrier layer described in the embodiments of FIGS. 1 to 10 . Detailsare not repeated herein.

As shown in FIG. 20 , FIG. 20 is a schematic structural diagram of abattery cell according to another embodiment of this application. Thebattery cell includes an enclosure 181 and one or more electrodeassemblies 182 accommodated in the enclosure 181. The enclosure 181includes a housing 1811 and a cover plate 1812. The housing 1811 has anaccommodating cavity, and the housing 1811 has an opening. That is, ahousing wall is not provided on this plane, so that the inside andoutside of the housing 1811 can communicate with each other and theelectrode assembly 182 can be accommodated in the accommodating cavityof the housing 1811. The cover plate 1812 and the housing 1811 arecombined at the opening of the housing 1811 to form a hollow chamber.After the electrode assembly 182 is accommodated in the enclosure 181,the enclosure 181 is filled with electrolyte and sealed.

The housing 1811 is determined depending on a shape obtained throughcombining the one or more electrode assemblies 182. For example, thehousing 1811 may be a hollow cuboid, a hollow cube, or a hollowcylinder. For example, when the housing 1811 is a hollow cuboid or cube,one of faces of the housing 1811 is an open face, that is, the face hasno housing wall, so that the inside and outside of the housing 1811communicate with each other. When the housing 1811 is a hollow cylinder,one of round sides of the housing 1811 is an open face, that is, theround side has no housing wall, so that the inside and outside of thehousing 1811 communicate with each other.

In another embodiment of this application, the housing 1811 may be madeof a conductive metal material or plastic. Optionally, the housing 1811may be made of aluminum or aluminum alloy.

For the structure of the electrode assembly 182, refer to relatedcontent of the electrode assembly described in the foregoing embodimentsof FIGS. 1 to 19 . Details are not repeated herein.

As shown in FIG. 21 , FIG. 21 is a schematic structural diagram of abattery module according to another embodiment of this application. Thebattery module 19 includes a plurality of interconnected battery cells191, and the plurality of battery cells 191 may be connected in series,in parallel, or in hybrid. Hybrid connection means being connected bothin series and in parallel. For the structure of the battery cell 191,refer to the battery cell described in the embodiment corresponding toFIG. 20 . Details are not repeated herein.

As shown in FIG. 22 , FIG. 22 is a schematic structural diagram of abattery according to another embodiment of this application. The batteryincludes a plurality of battery modules 19 and a box body. The box bodyincludes a lower box body 20 and an upper box body 30. The plurality ofbattery modules 19 may be connected in series, in parallel, or inhybrid. The lower box body 20 has an accommodating cavity, and the lowerbox body 20 has an opening, so that the plurality of battery modules 19that are connected can be accommodated in the accommodating cavity ofthe lower box body 20. The upper box body 30 and the lower box body 20are combined at the opening of the lower box body 20 to form a hollowchamber, and the upper box body 30 and the lower box body 20 are sealsafter being combined.

In another embodiment of this application, the battery may independentlysupply power to the electric apparatus, for example, being used forsupplying power to automobiles, and the battery may be referred to as abattery pack.

In another embodiment of this application, based on an electricityrequirement of the electric apparatus, a plurality of batteries areconnected and combined into a battery module to supply power to theelectric apparatus. In another embodiment of this application, thebattery module may alternatively be accommodated in one box body andpackaged.

For ease of description, the following embodiments are described byusing an example in which the electric apparatus includes a battery.

An embodiment of this application further provides an electricapparatus. For example, the electric apparatus may be an automobile, forexample, a new energy vehicle. The electric apparatus includes thebattery described in the foregoing embodiment. A battery used by theelectric apparatus may be the battery described in the embodimentcorresponding to FIG. 22 . Details are not repeated herein.

For example, as shown in FIG. 23 , FIG. 23 is a schematic structuraldiagram of an electric apparatus according to another embodiment of thisapplication. The electric apparatus may be a vehicle, and the vehiclemay be a fossil fuel vehicle, a natural gas vehicle, or a new energyvehicle, and the new energy vehicle may be a battery electric vehicle, ahybrid electric vehicle, an extended-range vehicle, or the like. Thevehicle includes a battery 2101, a controller 2102, and a motor 2103.The battery 2101 is used to supply power to the controller 2102 and themotor 2103, and acts as an operating power source and a driving powersource of the vehicle. For example, the battery 2101 is used to meetelectricity requirements for startup, navigation, and driving of thevehicle. For example, the battery 2101 supplies power to the controller2102, and the controller 2102 controls the battery 2101 to supply powerto the motor 2103. The motor 2103 receives and uses the power of thebattery 2101 as the driving power source of the vehicle, replacing orpartially replacing fossil fuel or natural gas to provide driving powerfor the vehicle.

As shown in FIG. 24 , FIG. 24 is a schematic flowchart of a method formanufacturing an electrode assembly according to another embodiment ofthis application. The method for manufacturing an electrode assemblyincludes the following content.

Step 221: Provide a positive electrode plate, a negative electrodeplate, and a barrier layer.

Step 222: Wind or stack the positive electrode plate and the negativeelectrode plate to form a bend region.

The bend region is provided with a barrier layer; and at least part ofthe barrier layer is located between the positive electrode plate andthe negative electrode plate that are adjacent to each other, and isused to prevent at least part of ions deintercalated from the positiveelectrode plate from being intercalated into the negative electrodeplate in the bend region.

In another embodiment of this application, a separator for isolating thepositive electrode plate and the negative electrode plate that areadjacent to each other is further provided; and the separator, thepositive electrode plate, and the negative electrode plate are wound orstacked together.

In another embodiment of this application, before the separator, thepositive electrode plate, and the negative electrode plate are wound orstacked together, the barrier layer is placed on one or two surfaces ofthe positive electrode plate or the negative electrode plate. Forexample, the barrier layer is adhered or coated to one or two surfacesof the positive electrode plate or the negative electrode plate.

For the related structure of the electrode assembly manufactured byusing the manufacturing method in this embodiment, refer to relatedcontent of the electrode assembly described in the embodimentscorresponding to FIGS. 1 to 19 . Details are not repeated herein.

As shown in FIG. 25 , FIG. 25 is a schematic structural diagram of adevice for manufacturing an electrode assembly according to anotherembodiment of this application. The device for manufacturing anelectrode assembly includes: a first providing apparatus 231, a secondproviding apparatus 232, a third providing apparatus 233, and anassembly apparatus 234.

The first providing apparatus 231 is configured to provide a positiveelectrode plate.

The second providing apparatus 232 is configured to provide a negativeelectrode plate.

The third providing apparatus 233 is configured to provide a barrierlayer.

The assembly apparatus 234 is configured to wind or stack the positiveelectrode plate and the negative electrode plate to form a bend region.

The bend region is provided with a barrier layer; and at least part ofthe barrier layer is located between the positive electrode plate andthe negative electrode plate that are adjacent to each other, and isused to prevent at least part of ions deintercalated from the positiveelectrode plate from being intercalated into the negative electrodeplate in the bend region.

In another embodiment of this application, the device for manufacturingan electrode assembly further includes a fourth providing apparatus 235,configured to provide a separator for isolating the positive electrodeplate and the negative electrode plate that are adjacent to each other.The assembly apparatus 234 is further configured to wind or stack thepositive electrode plate, the negative electrode plate, and theseparator to form the bend region.

In another embodiment of this application, there are two third providingapparatuses 233, and the two third providing apparatuses 233 areconfigured to provide the barrier layer and adhere or coat the barrierlayer onto two surfaces of the positive electrode plate or the negativeelectrode plate, respectively.

For the related structure of the electrode assembly manufactured byusing the manufacturing device in this embodiment, refer to relatedcontent of the electrode assembly described in the embodimentscorresponding to FIGS. 1 to 19 . Details are not repeated herein.

To sum up, the barrier layer is provided between the positive electrodeplate and the negative electrode plate that are adjacent to each otherand included in the electrode assembly of the battery cell, so that thebarrier layer blocks at least part of ions deintercalated from apositive electrode active material layer of the positive electrode platein the bend region during charging, and the ions blocked by the barrierlayer cannot be intercalated into a negative electrode active materiallayer of the negative electrode plate adjacent to the positive electrodeplate in the bend region. In this way, in a case that the negativeelectrode active material layer of the negative electrode plate fallsoff, lithium precipitation is reduced, thereby improving safetyperformance of battery cells and improving service life of the batterycells.

Those skilled in the art can understand that, although some of theembodiments described herein include some but not other featuresincluded in other embodiments, combinations of features of differentembodiments are meant to be within the scope of this application andform different embodiments. For example, in the claims, any one of theclaimed embodiments may be used in any combination.

The foregoing embodiments are merely intended for describing thetechnical solutions of this application, but not for limiting thisapplication. Although this application is described in detail withreference to the foregoing embodiments, persons of ordinary skill in theart should understand that they may still make modifications to thetechnical solutions described in the foregoing embodiments or makeequivalent replacements to some technical features thereof, withoutdeparting from the spirit and scope of the technical solutions of theembodiments of this application.

What is claimed is:
 1. An electrode assembly comprising: a positiveelectrode plate and a negative electrode plate wound or stacked to forma bend region; and a barrier layer provided at the bend region, at leastpart of the barrier layer being located between the positive electrodeplate and the negative electrode plate that are adjacent to each other,and being configured to prevent at least part of ions deintercalatedfrom the positive electrode plate from being intercalated into thenegative electrode plate in the bend region; wherein a ratio of athickness of the barrier layer to a porosity of the barrier layer islarger than or equal to 3.5 microns and smaller than or equal to 2000microns.
 2. The electrode assembly according to claim 1, furthercomprising: a separator isolating the positive electrode plate from thenegative electrode plate that are adjacent to each other; wherein thebarrier layer is attached to at least one of: one or two surfaces of thepositive electrode plate, one or two surfaces of the negative electrodeplate, or one or two surfaces of the separator.
 3. The electrodeassembly according to claim 2, wherein the porosity of the barrier layeris less than a porosity of the separator.
 4. The electrode assemblyaccording to claim 1, further comprising: a separator isolating thepositive electrode plate from the negative electrode plate that areadjacent to each other; wherein the barrier layer is independentlyprovided: between the positive electrode plate and the separator thatare adjacent to each other in the bend region, or between the negativeelectrode plate and the separator that are adjacent to each other in thebend region.
 5. The electrode assembly according to claim 1, wherein:the positive electrode plate and the negative electrode plate arecompacted and wound to form a winding structure; and the barrier layeris provided between the positive electrode plate and the negativeelectrode plate that are adjacent to each other on at least an innermostside of the bend region.
 6. The electrode assembly according to claim 5,wherein an innermost electrode plate in the bend region is the negativeelectrode plate.
 7. The electrode assembly according to claim 1, whereinthe barrier layer is one of a plurality of discontinuous barrier layersspaced apart from each other in a bending direction or in a directionperpendicular to the bending direction.
 8. The electrode assemblyaccording to claim 1, wherein the thickness of the barrier layer is 2 to200 microns.
 9. The electrode assembly according to claim 1, wherein thebarrier layer is provided with at least one through hole.
 10. Theelectrode assembly according to claim 9, wherein the porosity of thebarrier layer is 10% to 70%.
 11. The electrode assembly according toclaim 1, further comprising: a separator isolating the positiveelectrode plate from the negative electrode plate that are adjacent toeach other; wherein the barrier layer is attached to one or two surfacesof the separator.
 12. The electrode assembly according to claim 1,wherein two ends, in a direction perpendicular to a bending direction,of a negative electrode active material layer of the negative electrodeplate extend beyond corresponding ends of a positive electrode activematerial layer of the positive electrode plate.
 13. The electrodeassembly according to claim 1, wherein the barrier layer comprises twoends in a direction perpendicular to a bending direction, and one or twoof the two ends of the barrier layer extend beyond a positive electrodeactive material layer of the positive electrode plate.
 14. The electrodeassembly according to claim 1, wherein the barrier layer comprises twoends in a direction perpendicular to a bending direction, and a negativeelectrode active material layer of the negative electrode plate extendsbeyond one or two of the two ends of the barrier layer.
 15. Theelectrode assembly according to claim 1, wherein the barrier layer isdisposed opposite a largest-curvature portion of the negative electrodeplate.
 16. The electrode assembly according to claim 1, wherein thebarrier layer comprises at least one of inorganic oxide, binder, oradhesive tape.
 17. The electrode assembly according to claim 1, whereintwo ends, extending in a bending direction, of the barrier layer arelocated in the bend region.
 18. The electrode assembly according toclaim 1, wherein: the positive electrode plate and the negativeelectrode plate further form a flat region connected to the bend region;one end, extending in a bending direction, of the barrier layer islocated in the flat region; and another end, extending in the bendingdirection, of the barrier layer is located in the bend region or in theflat region.
 19. A battery cell, comprising: a housing having anaccommodating cavity and an opening; a cover plate configured to closethe opening of the housing; and the electrode assembly according toclaim 1 accommodated in the accommodating cavity.
 20. A battery,comprising: a box body; and the battery cell according to claim 19received in the box body.